now a threat to shipping traffic. the debris field is massive, stretching as much as 500 miles of the pacific, a distance of new york to michigan and it s headed straight for the united states. it will move with a powerful current, called the north pacific gyre. it will carry the remnants of 200,000 destroyed buildings, towards washington, then oregon and california. oceanographers say a year from now we ll see things that easily float, like boats, wood from houses and plastic children s toys. two years out, fishing supplies and nets will come ashore. and after three years, shoes, plastic furniture, even entire dining sets. so you have to imagine a city, say the size of seattle, put it through a grinder and what happens? you wind up with all kinds of debris. reporter: sad reminders of a disaster so enormous parts of japan will finally come to rest half a world away. neal karlinsky, abc news, tokyo. donald trump is turning up the heat over president obama s birth certificate once